1. Field of the Invention
The present invention relates to laser processing machines which can process sheet-like workpieces such as sheet metals by various methods such as cutting and piercing by use of laser beams produced by laser generators.
2. Description of the Prior Art
As is well-known, laser beams are widely used in industries to process a variety of materials, and they are used in the metal processing field to cut and pierce sheet-like workpieces such as sheet metals. Generally, a laser processing machine for processing sheet-like workpieces comprises a processing head assembly having a mirror and a focussing lens to focus and apply the laser beam from a laser generator to a workpiece to be processed and a work-table on which the workpiece is horizontally placed and moved to be processed. In laser processing, the laser beam which is generated by the laser generator is focussed and applied to the workpiece by the processing head assembly together with an exothermically reacting assisting gas such as oxygen gas (O.sub.2) so as to melt the workpiece. The assisting gas serves to enhance the processing action of the laser beam and remove slags and drosses or debris molten from the workpiece being processed and also to protect the face of the focussing lens from backscattered materials or metals. Also, the laser processing machine is preferably provided with a sucking means such as a vacuum pump for downwardly sucking the slags and drosses or debris which will be molten from the workpiece being produced.
With regard to the laser processing machine, one of the conventional disadvantages had been that the workpieces to be processed are liable to be scratched and damaged when horizontally moved on the work-table into and out of the processing area just beneath the processing head assembly. Although workpieces to be processed will be inevitably damaged more or less generally in any machines when moved on work-tables, the workpieces will be liable to be heavily damaged by the work-table in laser processing for several reasons. In laser processing, the workpieces will be heavily damaged by the work-table originally since they are pressed onto the work-table by the assisting gas which is kept blowing onto the workpiece during processing. Also they will be much more heavily damaged when they are pulled onto the work-table by a sucking means such as a vacuum pump for sucking the slags and drosses or debris. Furthermore, the workpieces to be processed in laser processing will be much more damaged by the slags and drosses or debris which will be produced molten form from the workpieces and will come to stick onto the work-table. Thus, it has been very disadvantageous in the laser processing machine that the workpieces will be damaged and spoiled in appearance in spite of the fact that the laser beam is used generally with a view of making accurate and fine cuttings.
Another conventional disadvantage with regard to the laser processing machine has been that the drosses or debris produced from the workpiece being processed are liable to ooze out and spread onto the underside of the workpiece from the kerf formed by the laser beam and will scratch and damage the work-table when the workpiece is moved there on. Accordingly, in this regard it has been disadvantageous that the workpiece will not only damage the work-table but also it cannot be freely and smoothly moved on the work-table because of friction between the workpiece and the work-table.